“What is collapsing right now?” the journalist Ben Judah asked on Twitter late Tuesday night, as it became clear that Donald Trump would be elected president of the United States.

The thing is, nobody’s quite sure, and nobody knows what might happen next. In an interview last week, Thomas Wright, a scholar of U.S. foreign policy at the Brookings Institution, told me he thought the international system that the United States helped establish after World War II might unravel over the course of a Trump presidency. This system, he explained, has been led by the United States—under both Democratic and Republican presidents—for seven decades, and consists of an open international economy, U.S. military alliances with Japan, South Korea, European NATO members, and other countries, and support for liberal rules and institutions that govern how countries conduct themselves. Wright argued that Trump has held a set of core beliefs since the 1980s that are hostile to this system: opposition to America’s alliance arrangements, opposition to free trade, and fondness for authoritarian leaders. The already strained system, Wright reasoned, might not survive if Trump implements what he pledged on the campaign trail.   

Wright said he wasn’t sure what might replace the U.S.-led international order if it collapsed, but he didn’t think it would be good:

[I’m] arguing that when you get rid of the architecture that made this possible, a lot of the positive elements in the world today will be very badly damaged and will come to an end. But there’s no real way of proving that. We can’t say if the alliances went away tomorrow, you can say with certainty that Russia will invade the Baltics or anything else. To a certain degree, it’s an assessment based on what has happened before in history and an assessment of the intentions of others.

But I would say over a 10-year period, what would probably happen is that the world would become much more dangerous in terms of other countries coming close to conflict with each other, and that there would be a lot of revisionism—countries testing borders and trying to protect their own interests unilaterally. There would be an increase in security competition, and that may very well drag the United States back in at a later stage. Even if the U.S. said it wanted nothing to do with Europe, nothing to do with Asia, the history from the early 20th century is that that ultimately can get out of control and can drag the United States in.

I [also] think the global economy would take a huge dive. There would probably be a very severe recession because the U.S. would not be guaranteeing the openness of the global economy. Trump’s position basically is: For the U.S. economy to do well, other countries must do worse. But our experience over the last 70-odd years is the opposite. It’s that in order for the U.S. and any individual country to do well, the global economy has to do well.

Others disagree, however. One of those people, of course, is Donald Trump, who argues that America’s alliances, trade deals, and attempts to solve the world’s problems have essentially made the United States a chump, draining the country of its blood and treasure. He doesn’t subscribe to the Washington consensus that the longstanding pillars of U.S. foreign policy constitute a win-win for America and the world. Instead, he suggests that international affairs is an every-country-for-itself struggle between winners and losers. “We will no longer surrender this country, or its people to the false song of globalism,” he declared during the campaign. “The nation-state remains the true foundation of peace and harmony.”

Or consider the view this morning of Peter van Ham, an expert on transatlantic relations at the Clingendael Institute in the Netherlands:

European leaders would have preferred Democratic candidate Hillary Clinton to win the U.S. presidential election because this would have given them more time to adjust to the gradual decline of the United States as a global hegemon. The question now is whether Europe’s leaders will be better off shocked out of their complacency by the victory of Republican candidate Donald Trump.

Today, the attitude among Europeans still seems to be that the United States will back Europe up with political support and military power if the going gets tough—be it with Russia, Iran, or (in future) China. A Clinton administration would have kept Europe’s leaders in their comfort zone, lulling them to sleep in the mistaken belief that the United States still guards their security and defense. A Trump administration will be a shock and, I think, a most welcome one. Trump has indicated that well-off Europeans have to leave their postmodern dreamworld and take responsibility for their borders, their security, and their defense. This requires not only commensurate defense spending but also a much-needed acceptance by Europe’s leaders that the world has become a tough place where realpolitik reigns.

Throughout this year’s presidential race, Trump’s critics have struggled to defend the cost and articulate the value of this elaborate international system—and America’s leadership of it—at a time when economic anxiety and war fatigue and isolationist sentiment are widespread among the American public. They’ve struggled to do these things in part because, for decades, they didn’t really have to; Republican and Democratic leaders largely took U.S. support for this system for granted. That is, until Trump challenged the conventional wisdom in Washington.

During a foreign-policy speech in June, for example, Hillary Clinton invoked that wisdom. She asserted that Americans wouldn’t want to live in a world that the United States doesn’t lead, but she didn’t make the detailed case for why she knew this to be true. “Trust me,” she said:

I believe in strong alliances; clarity in dealing with our rivals; and a rock-solid commitment to the values that have always made America great. And I believe with all my heart that America is an exceptional country—that we’re still, in Lincoln’s words, the last, best hope of earth. We are not a country that cowers behind walls. We lead with purpose, and we prevail.

And if America doesn’t lead, we leave a vacuum—and that will either cause chaos, or other countries will rush in to fill the void. Then they’ll be the ones making the decisions about your lives and jobs and safety—and trust me, the choices they make will not be to our benefit.

As Wright acknowledged to me, there’s no way of proving that a world without key elements of the current international system would be worse, for Americans and non-Americans, than the status quo. It is, as he noted, a theory shaped by history and a strong hunch. The debate over that theory—to the extent there was one before Trump came along—has long been speculative. If Trump governs as he campaigned, we may soon find out, in the real world, who was right.